Passive valve assembly with elongated vane

ABSTRACT

A passive valve assembly for a vehicle exhaust system includes an exhaust component that defines an exhaust gas flow path and a vane that is positioned within the exhaust gas flow path. The vane has an elongated body structure that has a greater height than width. The vane is positioned to provide a high percentage of coverage when closed but is able to pivot to a fully horizontal position when open to allow maximum flow.

RELATED APPLICATIONS

This application claims priority to provisional application No. 60/989,508 filed on Nov. 21, 2007.

TECHNICAL FIELD

The subject invention relates to a passive valve assembly in a vehicle exhaust system, and more particularly to a passive valve assembly that has an elongated vane to improve valve performance.

BACKGROUND OF THE INVENTION

Exhaust systems are widely known and used with combustion engines. Typically, an exhaust system includes exhaust tubes that convey hot exhaust gases from the engine to other exhaust system components, such as mufflers, resonators, etc. Mufflers and resonators include acoustic chambers that cancel out sound waves carried by the exhaust gases. Although effective, these components are often relatively large in size and provide limited nose attenuation.

Attempts have been made to improve low frequency noise attenuation by either increasing muffler volume or increasing backpressure. Increasing muffler volume is disadvantageous from a cost, material, and packaging space perspective. Increasing backpressure can adversely affect engine power.

Another solution for reducing low frequency noise is to use a passive valve assembly. Passive valve assemblies are either installed within a muffler, or are installed in a by-pass pipe configuration. Both of these known arrangements have certain disadvantages. Passive valves installed within mufflers are subjected to high temperatures, which limit the passive valve's effectiveness from material and cost perspectives. By-pass configurations are also disadvantageous from material cost and packaging perspectives.

Further, when the passive valve is used in a by-pass pipe configuration, challenges are presented when the passive valve is moved toward a fully open position. The passive valve includes a flapper valve body or vane that is positioned within the exhaust pipe, with the vane being pivotable between open and closed positions. The passive valve is spring biased toward the closed position, and when exhaust gas pressure is sufficient to overcome this spring bias, the vane is pivoted toward the open position. In by-pass configurations, the vane provides 100% coverage, i.e. complete blockage, of the exhaust component when in the closed position. When closed, exhaust gases can flow outside of the exhaust pipe that houses the vane via a by-pass pipe that is connected to the exhaust pipe at locations upstream and downstream of the vane.

When the vane is moved toward the fully open position potential interference challenges are presented by the shape of the pipe itself. Traditionally, the vane has been supported by a shaft mounted to a wall of the pipe, with the shaft defining a pivot axis of rotation. The pipe typically includes a curved pipe wall having an inner surface that defines the exhaust gas flow path. Due to the pivot axis of rotation being mounted close to the wall surface of the pipe, when the vane is pivoted, interference between the pipe and the vane can limit opening of the valve assembly. Limiting the opening angle is disadvantageous from a back pressure standpoint, in addition to failing to achieve a true fully open position for maximum flow.

Therefore, there is a need to provide a passive valve arrangement for a non-bypass configuration that can minimize the effect of the open angle limit to achieve minimum backpressure penalties. This invention addresses those needs while avoiding the shortcomings and drawbacks of the prior art.

SUMMARY OF THE INVENTION

A passive valve assembly for a vehicle exhaust system includes a vane having an elongated body structure. The elongated body structure has a greater height dimension than width dimension.

In one example, the elongated body structure comprises a generally oval-shaped disc. The oval-shaped disc comprises a curved upper edge, a curved lower edge, and a pair of opposing straight side edges that extend between the curved upper edge and the curved lower edge.

In one example, the elongated body structure includes a first portion to be coupled to a pivotable shaft. The elongated body structure extends from the first portion to a distal tip. The maximum vertical height dimension is defined by a line that extends from the first portion to the distal tip.

The vane is pivotable between a closed position where a maximum portion of the exhaust gas flow path is blocked by the vane and an open position where a minimum portion of the exhaust gas flow path is blocked by the vane. The closed position also defines a start position for the vane when there is no exhaust gas flow, or minimal exhaust gas flow. In one example, the exhaust gas flow path is 90%-97% blocked when the vane is in the start/closed position. Further, in one example configuration, the vane is positioned at a 20 degree start angle to provide a more rapid open area change. In this configuration, due to the elongated shape of the vane, the vane can be pivoted through a range of 20 to 90 degrees without interfering with walls of the exhaust component.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of one example of an exhaust component and passive valve assembly.

FIG. 2 shows a side view of an exhaust component with a stop for a vane.

FIG. 3 is a graph that shows blockage of an exhaust gas flow path vs. opening angle of the vane.

FIG. 4 is a schematic view of the exhaust component and passive valve assembly of FIG. 1 within an exhaust system.

FIG. 5 is a schematic end view of the exhaust component with the passive valve assembly being in a closed position.

FIG. 6 is a view similar to FIG. 5 but showing the passive valve assembly in an open position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, an exhaust component, such as an exhaust tube or pipe 10 includes an exhaust throttling valve, referred to as a passive valve assembly 12. The passive valve assembly 12 is movable between an open position where there is minimal blockage of an exhaust gas flow path 16 and a closed position where a substantial portion of the exhaust gas flow path 16 is blocked. The passive valve assembly 12 is resiliently biased toward the closed position and is moved toward the open position when exhaust gas flow generates a pressure sufficient enough to overcome the biasing force.

In the example shown, the exhaust pipe 10 comprises a single pipe body 14 that defines the exhaust gas flow path 16. In one example, the pipe body 14 includes a curved outer surface 14 a and a curved inner surface 14 b that defines the exhaust gas flow path 16. In one example, the pipe body 14 has a circular cross-section.

The passive valve assembly 12 includes a valve body or vane 18 that blocks a portion of the exhaust gas flow path 16 when in the closed position. As discussed above, the vane 18 is pivoted toward the open position to minimize blockage of the exhaust gas flow path 16 in response to pressure exerted against the vane 18 by exhaust gases.

In one example, the vane 18 is fixed to a shaft 20 with a connecting arm, shown schematically at 22 in FIG. 1. A slot 24 is formed within the curved outer surface 14 a of the pipe body 14. A housing 26, shown in this example as a square metal structure, is received within this slot 24 and is welded to the pipe body 14. Other housing configurations could also be used. The shaft 20 is rotatably supported within the housing 26 by first 28 and second 30 bushings or bearings and defines an axis of rotation A.

The first bushing 28 is positioned generally at a first shaft end 32. The first bushing 28 comprises a sealed interface for the first shaft end 32. The shaft 20 includes a shaft body 34 that has a first collar 36 and a second collar 38. The first bushing 28 includes a first bore that receives the first shaft end 32 such that the first collar 36 abuts directly against an end face of the first bushing 28 to provide a sealed interface. As such, exhaust gases cannot leak out of the first bushing 28 along a path between the shaft 20 and first bushing 28.

The second bushing 30 includes a second bore through which the shaft body 34 extends to a second shaft end 40. The second collar 38 is located axially inboard of the second bushing 30. The shaft 20 extends through the second bore to an axially outboard position relative to the second bushing 30. A resilient member, such as a spring 42 for example, is coupled to the second shaft end 40 with a spring retainer 44. The spring retainer 44 includes a first retainer piece 46 that is fixed to the housing 26 and a second retainer piece 48 that is fixed to the second shaft end 40. One spring end 50 is associated with housing 26 via the first retainer piece 46 and a second spring end (not viewable in FIG. 1 due to the spring retainer 44) is associated with the shaft 20 via the second retainer piece 48.

The vane 18 comprises a body structure 60, such as a disc-shaped body for example, which includes a first portion 62 that is coupled to the shaft 20 with the connecting arm 22. The body structure 60 extends from the first portion 62 to a second portion that comprises a distal tip 64. As such, the tip 64 comprises a portion of the body structure 60 that is furthest from the axis of rotation A.

A stop 66 is supported by the pipe body 14 and is positioned within the exhaust gas flow path 16. The stop 66 defines the starting/closed position for the vane 18. The tip 64 of the vane 18 engages the stop 66 when the spring 42 returns the vane 18 from the open position to the closed position.

In one example, as shown in FIGS. 1 and 2, the stop 66 comprises a ramped surface 68 that begins at the inner surface 14 b at a position upstream from the vane 18 and extends outwardly away from the inner surface 14 b and toward the vane 18. The ramped surface 68 then transitions into a stopper end surface 70 that extends back towards the inner surface 14 b. The tip 64 of the vane 18 engages the stopper end surface 70 when in the closed position. This also defines the starting position for the vane 18 when there is no exhaust gas flow, or only a minimal amount of exhaust gas flow that is not sufficient to overcome the biasing force of the resilient member.

As shown in FIG. 2, the ramped surface 68 and the stopper end surface 70 are angled relative to the inner surface 14 b of the pipe body 14. The pipe body 14 defines a pipe centerline C, which is shown in FIG. 2. The ramped surface 68 is positioned at a ramp angle that is within a range of 10 to 45 degrees relative to the pipe centerline C. Similarly, the stopper end surface 70 is positioned at an angle relative to the pipe centerline C to define the start position. This will be discussed in greater detail below. In one example, the ramped surface 68 and the stopper end surface 70 are obliquely orientated relative to the inner surface 14 b of the pipe 10 and relative to the pipe centerline C.

In one example, a pad 72 is supported on the stopper end surface 70 to provide a cushioned surface to engage the tip 64 of the vane 18. The pad 72 can be made from a mesh material or other similar material, for example, and can be attached to the stopper end surface 70 with any type of attachment method suitable for use within an exhaust component.

The stop 66 is positioned at the tip 64 of the vane 18 to minimize closing forces. By positioning these contact surfaces as far as possible from the axis of rotation A, contact forces are reduced, which in turn increases durability. Further, the upstream ramped surface 68 of the stop 66 reduces backpressure, turbulence, and the generation of additional flow noise.

The vane 18 is positioned to provide an exhaust gas flow path that is 80%-97% blocked when the vane 18 is in the start/closed position, as well as being positioned to provide a rapid open area change with only a small angle change at initial vane lift-off from the start/stop position. The vane 18 is movable between a fully closed position where a maximum portion of the exhaust gas flow path 16 is blocked by the vane 18 and a fully open position where a minimum portion of the exhaust gas flow path 16 is blocked by the vane 18. As discussed above, the closed position also corresponds to the start position for the passive valve assembly when there is no, or low, exhaust gas flow. In this start position, the vane 18 is orientated to be non-perpendicular to a direction of the exhaust gas flow, which is indicated at 80 in FIG. 2.

As discussed above, the pipe body 14 defines a pipe centerline C that extends along a length of the exhaust pipe 10. The vane 18 is obliquely orientated relative to a plane P that is perpendicular to the pipe centerline C at the valve position in the exhaust gas flow path 16. As shown in FIG. 2, the vane 18 is orientated at an angle {acute over (α)} relative to the plane P that is within a range of 10 to 35 degrees. This angle {acute over (α)} is defined by the angle of the stopper end surface 70.

As shown in FIG. 3, orientating the vane 18 in such a manner provides significant operational advantages in additional to improving noise reduction. Small opening angle changes provide rapid increases in open area, i.e. blockage of the exhaust gas flow path 16 quickly decreases with only very small changes in the opening angle. This significantly reduces flutter behavior, which has been associated with a rate of change of open area from a start position.

In one example, shown in FIG. 4, the passive valve assembly 12 is positioned within an exhaust component 82. In this example, the exhaust component 82 comprises a pipe that has a first end 84 coupled to a first exhaust component 86 and a second end 88 coupled to a second exhaust component 90. The pipe comprises a non-bypass configuration with the pipe defining a sole exhaust gas flow path 92 between the first 86 and the second 90 exhaust components. A direction of exhaust gas flow is indicated by arrows 94. As such, the passive valve assembly 12 comprises the only valve assembly that is positioned in the gas flow path 92 between the first 86 and second 90 exhaust components.

In this configuration, as discussed above, the vane 18 is only pivoted from the start/closed position toward the open position in response to an exhaust gas flow 94 that exceeds a biasing force of the resilient member. As shown, the stop 66 is positioned to hold the vane 18 at the oblique starting angle. The resilient member returns the vane 18 into abutting engagement with the stop 66 when the exhaust gas flow is less than the biasing force of the resilient member.

Further, the vane 18 is uniquely configured to provide pivoting capability to a fully horizontal open position without interference with the curved inner surface 14 b of the pipe 10. As shown in FIG. 5, the vane 18 has an elongated body structure 100 that is defined by a maximum vertical height dimension H and a maximum horizontal width dimension W that is perpendicular to the maximum vertical height dimension H. The elongated body structure 100 has a greater maximum vertical height dimension H than maximum horizontal width dimension W.

The elongated body structure 100 has a generally oval-shape and includes a curved upper edge 102, a curved lower edge 104, and a pair of opposing straight side edges 106 that extend between the curved upper edge 102 and the curved lower edge 104. In this configuration, the straight side edges 106 are orientated to be perpendicular to the axis of rotation A but do not intersect the axis of rotation A. This is due to the use of the connecting arm 22 to couple the vane 18 to the shaft 20.

As discussed above, the elongated body structure 100 of the vane includes the first portion 62 that is coupled to the shaft 20 with the connecting arm 22. This first portion 62 extends to the distal tip 64 that engages the stop 66. The maximum vertical height dimension H is defined by a line that extends from the first portion 62 to the distal tip 64. As such, the maximum vertical height dimension H has a component that is generally perpendicular to a direction of the exhaust gas flow.

As discussed above, the vane 18 is pivotable between a closed position where a maximum portion of the exhaust gas flow path is blocked by the vane 18 and an open position where a minimum portion of the exhaust gas flow path is blocked by the vane 18. The fully closed position is shown in FIG. 5 and the fully open position is shown in FIG. 6. The exhaust gas flow path is 80%-97% blocked when the vane 18 is in the closed position.

In one example, the exhaust gas flow path is at least 90% blocked, and the start angle for the vane 18 (defined by the stopper end surface 70 as described above) is at least 20 degrees. In this configuration the vane 18 is easily pivotable from the start angle of 20 degree to a 90 degree angle relative to the plane P to achieve a fully horizontal open position as shown in FIG. 6. Due to the elongated shape of the vane 18 with the straight side edges 106, this pivoting occurs without any interference from the curved inner surface 14 b of the pipe 10. Further, when the vane 18 is at this 90 degree position, it provides the least amount of blockage to maximize exhaust gas flow.

Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

1. A passive valve assembly for a vehicle exhaust system comprising: a vane to be positioned within an exhaust gas flow path, said vane having an elongated body structure defined by a maximum vertical height dimension and a maximum horizontal width dimension that is perpendicular to said maximum vertical height dimension, said maximum vertical height dimension being greater than said maximum horizontal width dimension.
 2. The passive valve assembly according to claim 1 wherein said elongated body structure comprises a generally oval-shaped disc.
 3. The passive valve assembly according to claim 2 wherein said oval-shaped disc comprises a curved upper edge, a curved lower edge, and a pair of opposing straight side edges that extend between said curved upper edge and said curved lower edge.
 4. The passive valve assembly according to claim 1 wherein said vane is resiliently biased toward a closed position and is movable toward an open position in response to an increase in exhaust gas flow sufficient to overcome the biasing force, and wherein said maximum vertical height dimension is generally perpendicular to a direction of the exhaust gas flow.
 5. The passive valve assembly according to claim 1 wherein said elongated body structure includes a first portion to be coupled to a pivotable shaft, said first portion extending to a distal vane tip, and wherein said maximum vertical height dimension is defined by a line extending from said first portion to said distal vane tip.
 6. A passive valve assembly for a vehicle exhaust system comprising: an exhaust component having a curved inner wall surface defining an exhaust gas flow path; a shaft supported by a wall of said exhaust component, said shaft defining an axis of rotation; and a vane positioned within the exhaust gas flow path, said vane having an elongated body structure that extends from a first portion coupled to said shaft to a distal tip, and said elongated body structure being defined by a maximum width dimension and a maximum height dimension that extends in a direction from said first portion to said distal tip, and wherein said maximum height dimension is greater than said maximum width dimension.
 7. The passive valve assembly according to claim 6 wherein said elongated body structure includes a curved upper edge, a curved lower edge, and a pair of opposing straight side edges that extend between said curved upper edge and said curved lower edge.
 8. The passive valve assembly according to claim 7 wherein said pair of opposing straight side edges are perpendicular to said axis of rotation.
 9. The passive valve assembly according to claim 7 wherein said pair of opposing straight side edges do not intersect said axis of rotation.
 10. The passive valve assembly according to claim 6 wherein said vane is pivotable between a fully closed position where a maximum portion of the exhaust gas flow path is blocked by said vane and a fully open position where a minimum portion of the exhaust gas flow path is blocked by said vane, and wherein said exhaust gas flow path is 80%-97% blocked when said vane is in said fully closed position.
 11. The passive valve assembly according to claim 10 wherein said exhaust gas flow path is 90-97% blocked when said vane is in said fully closed position.
 12. The passive valve assembly according to claim 6 wherein said fully closed position comprises a start position for the passive valve assembly, and wherein said vane is obliquely orientated to a plane that is perpendicular to a centerline of said exhaust component when in said start position.
 13. The passive valve assembly according to claim 12 wherein said vane is orientated to be at an angle relative to said plane with said angle being within a range of 10 to 35 degrees.
 14. The passive valve assembly according to claim 13 wherein said angle is at least 20 degrees and wherein said vane is pivotable to an angle that is 90 degrees relative to said plane when said vane is in said fully open position.
 15. The passive valve assembly according to claim 6 wherein said vane is positioned within said exhaust component in a non-bypass arrangement, and wherein the passive valve assembly comprises the only valve assembly positioned within said exhaust component.
 16. The passive valve assembly according to claim 15 wherein said exhaust component comprises a non-bypass pipe with a first end to be connected to a first exhaust component and a second end to be connected to a second exhaust component and wherein said non-bypass pipe comprises the sole exhaust gas flow path between the first and the second exhaust components.
 17. The passive valve assembly according to 6 including a resilient member supported by said shaft that biases said vane toward said fully closed position, said vane only being pivoted about said axis of rotation from said fully closed position towards said fully open position in response to an exhaust gas flow that exceeds a biasing force of said resilient member.
 18. The passive valve assembly according to claim 17 including a stop supported by said exhaust component and positioned within said exhaust gas flow path to engage said distal tip of said elongated body structure, said stop being positioned to hold said vane at an oblique angle relative to a plane that is perpendicular to a centerline of said exhaust component. 